#include <iostream>

#include <algorithm>

#define MAXN 50005

using namespace std;

struct node

{

    int x;

    int y;

    bool boo;

};

bool op(node a,node b);

node _node[MAXN];

int main()

{

    //freopen("acm.acm","r",stdin);

    int i;

    int j;

    int n;

    int b;

    int e;

    scanf("%d",&n);

    for(i = ; i < n; ++ i)

    {

        scanf("%d",&_node[i].x);

        scanf("%d",&_node[i].y);

    }

    sort(_node,_node+n,op);

    for(i = ; i < n; ++ i)

    {

        if(i == )

        {

            b = _node[i].x;

            e = _node[i].y;

        }

        else

        {

            if(_node[i].x <= e && _node[i].y >= e)

            {

                e = _node[i].y;

            }

            else if(_node[i].x > e)

            {

                printf("%d %d\n",b,e);

                b = _node[i].x;

                e = _node[i].y;

            }

        }

    }

//    cout<<b<<" "<<e<<endl;

    printf("%d %d\n",b,e);

}

bool op(node a,node b)

{

    if(a.x == b.x)

    {

        return a.y > b.y;

    }

    return a.x < b.x;

}